1. Field of the Invention
The present invention is in the field of cable and connector components for high-speed data communications. In particular, the invention is in the field of cable and connector components in which undesired reactances and crosstalk are compensated for.
2. Description of the Related Art
The deployment of new computer network architectures has increased the demand for improved data communication cables and connectors. Conventional cables and connectors have been used for voice transmission and for low-speed data transmission in the range of a few megabits per second. However, because conventional data cables and connectors were inadequate for high-speed, bit-error-free data transmission within current or proposed network architectures, new types of high-speed data communication cables and connectors have been developed. Such new cables or connectors need to meet specific requirements such as low attenuation, acceptable return loss, low crosstalk and good EMC (Electro-Magnetic Coupling) performance parameters. They also need to meet specific requirements with respect to impedance, delay, delay skew and balance.
Cables for transmitting high-speed digital signals frequently make use of twisted pair technology, because twisted pairs of conductors eliminate some types of crosstalk and other noise. Crosstalk is a measure of undesirable signal coupling from one signal carrying medium to another. In a twisted pair, each conductor of the twisted pair carries an information signal that is equal in amplitude and 180xc2x0 out of phase with the counter-part signal carried by the pair. That is, each twisted pair carries differential signals. Ideally, the proximity of the twisted pairs to each other causes crosstalk to affect both conductors of the twisted pair equally. Thus, this noise ideally occurs in both conductors of the twisted pair creating a common mode signal. Crosstalk coupled to the same pair within the same cable can be compensated by adaptive amplifier techniques that substantially reject common mode signals. However, differential noise, which is noise that does not occur equally in both conductors of a twisted pair, cannot be compensated for with such techniques.
Several different measures of crosstalk have been developed to address concerns arising in different cables, communications systems and environments. One useful measure of crosstalk is near-end crosstalk (NEXT). Near-end crosstalk is a measure of the signal coupled between two media, e.g., two twisted pairs of conductors, within a cable. A signal is injected into one end of the first medium and the coupled signal is measured at the same end of the second medium. Another useful measure of crosstalk is far-end crosstalk (FEXT). Like NEXT, FEXT is a measure of the signal coupled between two media within a cable. A signal is injected into one end of the first medium and the coupled signal is measured at the other end of the second medium. Other measures of crosstalk exist, including measures for crosstalk of other types. For example, there is so-called alien crosstalk, which is coupling into a cable from outside of a cable, such as from another cable, which may also be of interest.
A connector usually includes a plug that is mated with a jack that has a receptacle-type opening for mating with the plug. The plug and jack usually include a housing having a wire-receiving end, a contact-terminating end, a passageway for communicating internally between the respective ends of the plug, and a plurality of leads that couple contact terminals at the contact-terminating end of the plug to wire connector terminals at the wire-receiving end of the plug.
Modern data networks typically have connector systems including data transmission cables built into the walls of a building, which are terminated by a connector jack to enable flexible use of space. Individual computers are typically connected to the data network using a patch cord cable assembly terminated with a connector plug, by inserting the connector plug into the connector jack. A patch cord cable assembly typically includes a data transmission cable, typically with four twisted pairs of conductors, and two plugs. The four twisted pairs may be wrapped either in a flat or a round insulating jacket. The jacket may optionally include a drain wire and a surrounding shield for use with a shielded plug. A goal with such a patch cord is typically to minimize EMC and EMI (Electro-Magnetic Interference) to the outside environment as required by various regulations.
Many such related art connector systems have been used to transmit low-frequency data signals, and have exhibited no significant crosstalk problem between conductors of different twisted pairs at low frequencies. However, when such connector systems are used for transmission of high-frequency data signals, crosstalk between different twisted pairs increases dramatically. For such connector systems, this problem typically is caused by the construction of the connectors, wherein the leads within the connector are substantially parallel and in close proximity to each other, thereby producing excessive crosstalk between them.
It is common practice in such connector systems, according to a pre-established standard for connectors (and in particular the connector contact terminals), to configure each of the plug and jack with rows of the contact terminals which are connected with corresponding rows of the wire connector terminals, through the parallel leads in the connector element. However, there is a certain capacitive coupling that exists between the parallel leads of such a connector element. In addition, since it is a desire that the connector be as small as possible, this accentuates the capacitive coupling problem because the required small dimensions result in a small distance between the leads of the connector element, and thus a relatively high capacitance between the leads. In addition, while the capacitance between adjacent leads of a connector element may be relatively high, the capacitance may also be undesirably low between non-adjacent leads of the connector element. For example, it may be desirable to have a higher capacitance between non-adjacent leads to provide compensation for capacitance introduced elsewhere.
Also, problems occur not only with the capacitance between the leads of the connector element, but also with respect to the mutual inductance between the leads and, in particular, between pairs of the leads, as well as the inductance of the leads themselves, which is a function of the width of the leads. The mutual inductance between the pairs of leads is a function of a coil effect between the pairs of the leads. Thus, the pre-established standard for the contact terminals and the size of the connector do not create ideal conditions in the connector element.
A number of popular modular, multi-conductor connectors have been used in telecommunications applications and data transmission applications. Such connectors include 4-conductor, 6-conductor and 8-conductor types, commonly referred to as RJ-22, RJ-11, and RJ-45 connectors. Referring to FIG. 1, there is illustrated as in known in the related art an 8-conductor RJ-45-type connector 5, which includes a jack 30 and a plug 10. Each is typically made from a plastic body surrounding and supporting eight leads (not illustrated). Specifically, the RJ-45-type plug 10 has eight leads located side-by-side. Each lead is connected to a wire connecting portion at one end of the plug, and a contact terminal at a second end of the plug. The RJ-45-type jack 30 also has eight conductive leads (not illustrated) typically located side-by-side, and each lead also is connected to a wire connecting terminal at a first end of the jack and to a contact terminal arranged as a cantilever spring, at a second end of the jack. Typically, each of the eight wire connector terminals of the plug are connected to a corresponding conductor of the four twisted pairs of conductors of the patch cord cable, in a standard arrangement.
As mentioned above, the related art RJ-45 plug and jack typically have the leads placed straight in parallel and in close proximity to each other. The close proximity increases the parasitic capacitance between the leads, and the straight parallel arrangement increases the mutual inductance between the leads. These parasitic capacitances and mutual inductances are a principal source of differential noise, due to coupling. Specifically, crosstalk occurs between the electric field of one lead and the electric field of an adjacent lead within the jack or plug. The crosstalk coupling is inversely proportional to the distance between the interfering leads. The signal emitted from one emitting lead may be capacitively and/or inductively coupled to a another lead that is connected to a first conductor of a twisted pair of conductors. However, since a lead connected to a second conductor of the twisted pair of conductors is at a different distance from the emitting lead, this creates a differential coupling in the twisted pair of conductors.
There has also been in the interest of both manufacturers and end users, standardization of equipment and quantification of the emission parameters, including attenuation, near-end crosstalk and return loss for unshielded twisted pair (UTP) connectors. For example, the Electronic Industry Association (EIA) Telecommunication Industry Association (TIA), in an attempt to reach cross-manufacturer compatibility, set EIA/TIA-568-A which mandates a maximum coupling level in, for example, a category 5 plug and connector. The connectors of the related art have included counter-coupling or compensation structures designed to minimize the overall coupling inside the connectors. However, in the connectors of the related art, the effectiveness of this counter-coupling compensation has been limited, for example, because there is a variability in the different plugs"" crosstalk coupling.
Accordingly, there is a need for an improved connector including an improved jack and/or an improved plug that can provide improved crosstalk performance of the entire connector.
It is to be understood that according to this specification, a connector is a device that connects a transmission medium such as, for example, a communications cable to another communications device such as, for example, a personal computer or to another communication medium. It is also to be understood that according to this specification, a connector is made up of mating connector elements typically referred to as a plug and a jack, and therefore it is to be understood that a connector element according to this specification can be either a plug or a jack of a connector.
According to the invention, one connector element for making a connection between electrical conductors in a communications network has a front, a rear and a length between the front and the rear. The connector element includes a plurality of contact terminals arranged at the front of the connector element and that are configured for connection with corresponding contact terminals of a mating connector element. The connector elements also includes a plurality of wire connector terminals arranged at substantially the rear of the connector element. The connector element further includes a plurality of leads, each lead connecting a corresponding wire connector terminal with a corresponding contact terminal, wherein the plurality of leads include three layers of leads that in combination provide a compensation structure that reduces noise or crosstalk introduced by a combination of the connector element and the mating connector element.
According to the invention, another connector element for making a connection between electrical conductors in a communications network has a front, a rear and a length between the front and the rear. The connector element includes a plurality of contact terminals arranged at the front of the connector element and that are configured for connection with corresponding contact terminals of a mating connector element. The connector elements also includes a plurality of wire connector terminals arranged at substantially the rear of the connector element. The connector element further includes a plurality of leads, each lead connecting a corresponding wire connector terminal with a corresponding contact terminal. The plurality of leads are fixed in a permanent relationship so as to fix the electrical performance of the connector element, by an integrally formed housing enclosing at least a portion of the plurality of leads, that holds the plurality of leads in the fixed relationship.
According to the invention, another connector element for making a connection between electrical conductors in a communications network has a front, a rear and a length between the front and the rear. The connector element includes a plurality of contact terminals arranged at the front of the connector element and that are configured for connection with corresponding contact terminals of a mating connector element. The connector element also includes a plurality of wire connector terminals arranged at substantially the rear of the connector element. The connector element further includes a plurality of leads, each lead connecting a corresponding wire connector terminal with a corresponding contact terminal. The plurality of leads include means for sequentially compensating for noise or crosstalk introduced by a combination of the connector element and the mating connector element.
According to the invention, another connector element for making a connection between electrical conductors in a communications network has a front, a rear and a length between the front and the rear. The connector element includes a plurality of contact terminals arranged at the front of the connector element and that are configured for connection with corresponding contact terminals of a mating connector element. The connector element also includes a plurality of wire connector terminals arranged at substantially the rear of the connector element. The connector element further includes a plurality of leads, each lead connecting a corresponding wire connector terminal with a corresponding contact terminal. A lead of a pair of leads of the plurality of leads includes in series, a first capacitive plate and a second capacitive plate, wherein the first capacitive plate and the second capacitive plate in combination with corresponding capacitive plates of another pair of leads, form first and second capacitors. The lead in combination with a lead of the other pair of leads also form an inductive loop. The first capacitor, the inductive loop and the second capacitor in combination compensate for noise or crosstalk introduced by a combination of the connector element and the mating connector element.
According to the invention, another connector element for making a connection between electrical conductors in a communications network has a front, a rear and a length between the front and the rear. The connector element includes a plurality of contact terminals arranged at the front of the connector element and that are configured for connection with corresponding contact terminals of a mating connector element. The connector element also includes a plurality of wire connector terminals arranged at substantially the rear of the connector element. The connector element further includes a plurality of leads, each lead connecting a corresponding wire connector terminal with a corresponding contact terminal. The plurality of leads include a plurality of layers of leads that in combination provide a compensation structure that reduces noise or crosstalk introduced by a combination of the connector element and the mating connector element. In addition, at least two of the plurality of wire connector terminals include means for providing a capacitance between the at least two wire connector terminals.
According to the invention, another connector element for making a connection between electrical conductors in a communications network has a front, a rear and a length between the front and the rear. The connector element includes a plurality of contact terminals arranged at the front of the connector element and that are configured for connection with corresponding contact terminals of a mating connector element. The connector elements also includes a plurality of wire connector terminals arranged at substantially the rear of the connector element. The connector element further includes a plurality of leads, each lead connecting a corresponding wire connector terminal with a corresponding contact terminal. The plurality of leads include a plurality of layers of leads that in combination provide a compensation structure that reduces noise or crosstalk introduced by a combination of the connector element and the mating connector element. In addition, at least two of the wire connector terminals include enlarged portions of the wire connector terminals that narrow a spacing between the at least two wire connector terminals and that provide a parallel plate capacitance between adjacent edges of the at least two wire connector terminals.